Differential subcellular localization of RIC-3 isoforms and their role in determining 5-HT3 receptor composition.
J Biol Chem
; 282(36): 26158-66, 2007 Sep 07.
Article
en En
| MEDLINE
| ID: mdl-17609200
ABSTRACT
RIC-3 has been identified as a chaperone molecule involved in promoting the functional expression of nicotinic acetylcholine and 5-HT(3) receptors in mammalian cells. In this study, we examined the effects of RIC-3a (isoform a) and a truncated isoform (isoform d) on RIC-3 localization, mobility, and aggregation and its effect on 5-HT3 receptor composition in mammalian cells. Human RIC-3a possesses an amino-terminal signal sequence that targets it to the endoplasmic reticulum where it is distributed within the reticular network, often forming large diffuse "slicks" and bright "halo" structures. RIC-3a is highly mobile within and between these compartments. Despite the propensity for RIC-3a to aggregate, its expression enhances the level of surface 5-HT3A (homomeric) receptors. In contrast, RIC-3a exerts an inhibitory action on the surface expression of heteromeric 5-HT3A/B receptors. RIC-3d exhibits an altered subcellular distribution, being localized to the endoplasmic reticulum, large diffuse slicks, tubulo-vesicular structures, and the Golgi. Bidirectional trafficking between the endoplasmic reticulum and Golgi suggests that RIC-3d constitutively cycles between these two compartments. In support of the large coiled-coil domain of RIC-3a being responsible for protein aggregation, RIC-3d, lacking this cytoplasmic domain, does not aggregate or induce the formation of bright aggregates. Regardless of these differences, isoform d is still capable of enhancing homomeric, and inhibiting heteromeric, 5-HT3 receptor expression. Thus, both isoforms of RIC-3 play a role in determining 5-HT3 receptor composition.
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Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Receptores de Serotonina 5-HT3
/
Péptidos y Proteínas de Señalización Intracelular
/
Retículo Endoplásmico
/
Aparato de Golgi
Límite:
Animals
/
Humans
Idioma:
En
Revista:
J Biol Chem
Año:
2007
Tipo del documento:
Article
País de afiliación:
Reino Unido